Outside the Universe

The Universe is expanding. Expanding to where ? There must be an empty space where the universe will expand itself to, right ? Think about a baloon. Let's say the universe is everything inside the baloon. The baloon expands, because it has room to expand. If the universe is infinit, the empty space it has around it to expand to is also infinit. What is this empty space ?

Staff: Mentor

The inverse is not shaped like the space inside a balloon, it is shaped more like the surface of the balloon, but in 3d instead of 2d. Hence, there is no edge - no boudary for there to be something "outside" of.

The inverse is not shaped like the space inside a balloon, it is shaped more like the surface of the balloon, but in 3d instead of 2d. Hence, there is no edge - no boudary for there to be something "outside" of.

I've never been able to grasp this argument. Even the surface of the ballon expands into something else.

If you're trying to say we have no way to measure an "outside" of the universe, so it might as well not exist for our purposes, that's fine. But, that isn't what you're saying.

Here's a related mental exercise. Imagine the expansion of the universe was halted, everything frozen in time where it is right now. Then, go in a straight line in any direction you wish. Would you end up back where you started eventually? Would you run into a boundry? What would happen?

Some say the big bang came to be because of a random fluctuation in vacuum energy, or that "something" is more stable than "nothing." If that is the case, what is to stop (some time in the distant future, even by cosmological timescales) another "big bang" to develop inside of our universe? Would the hypothetical denizens of that universe claim that they aren't expanding into anything? That there is no "outside?"

I've never been able to grasp this argument. Even the surface of the ballon expands into something else.

It's an analogy which, of course, is not exact.

Imagine the expansion of the universe was halted, everything frozen in time where it is right now. Then, go in a straight line in any direction you wish. Would you end up back where you started eventually? Would you run into a boundry? What would happen?

If the universe is closed, then yes, you will at some time go back to where you started. If the universe is flat, then you would continue forever. Current observations do not enable us to say which of the above is true. One of the bonuses of the balloon analogy is it gives us an example of a finite unbounded universe.

I think the vacuum is not a simple empty one, but it has a property of inertia that is expanding activity wants to continue, like moving objects move continuously. And I am satisfied limiting myself in the universe.

The Universe is not expanding to ‘where’. Rather it makes the ‘where’ as it expands.

The expansion creates time and space as it expands. To ask what is on the other side means nothing.

To paraphrase; to ask what is on the other side is like asking what is 15 kilometers South of the South Pole. It sounds like a good question but in essence really does not have a legitimate answer because of the question in the first place.

As put it, freeze or stop time. This sounds good, but think about it. If time exists at all then in flows in a direction and is measurable. This evokes a problem. If time flows, then it can not stop.
The premise means nothing.

Simple example;

If I were to stop time, then I would have to stop it for a measurable period. Perhaps a week, month, year, what ever. Yet if I stopped it, there is no appreciable time then to measure the stopped period.

I think these kinds of problems deal more with us than the universe. Our comprehension of dimensional space is closely related to our evolution. We did not require higher dimensional evolution. There for we are not ‘wired’ for it.

So, the best thing is try to grasp the concept (which I have a difficult job with) there is no other side. There is no wall, no barrier, no time, no other side, no nothing.
It does not exist. The existence is made as the universe expands.

I know my explanation ‘sucks’ but I have to keep it philosophical because there are no formulas to analogize it in.
A philosophical question is best answered with a philosophical answer.

Ok, instead of "freezing time" just imagine the state of things at present at further and further distances from you. You see the sun as it was 8 minutes ago, but it exists now. Imagine how it is now. Now, imagine a further away star. Continue along in a linear fashion. Keep going out to where we see quasars right now. They will look dramatically different than we currently see them. Keep going out.

No ad hoc "time freezing" needed, it is just a mental excercise.

It seems to me we'd either hit a boundry or go around in a big circle.

I may be completely wrong here, but I think the more correct answer to the original question is something like "Nobody knows for sure... Furthermore, it may not even be a meaningful question to begin with. We're still working out the details. "

Ok, instead of "freezing time" just imagine the state of things at present at further and further distances from you. You see the sun as it was 8 minutes ago, but it exists now. Imagine how it is now.

You see, this is the problem. I can't imagine it now. I have absolutely no way of knowing it 'now'.
Any information form the sun is only pertinent to me in my frame of reference.

This is like a mathematical anomaly; if I launch a projectile against a wall the distance is always divisible by 2, yet the projectile will hit the wall.

Then, what is the definition of 'now'. If you are looking at the moon, if you are looking at a tree across the street, if you are looking at an object just before your eyes. The answer is 'no' to all of these.

That is why these type of conversations are fruitless. There is point, counter point, that will eventually get into a loop, and excuse the pun turn back on itself.

This reminds me of a question someone asked me a few days ago. "Why does light travel at a particular speed and not a kilometer / hr more or less".
My answer was simple, " I have no idea. Things just work in a particular way".

Furthermore, it may not even be a meaningful question to begin with.

This is exactly what I said!

Answers to some things can be meaningless, which poses the premise, some questions can be meaningless.

I am not being obnoxious or fecicious here but perhaps ask the same question on a philosophical or religious forum. Perhaps they can give you a better answer.

However, I still do appreciate your problem with the universe 'size' or barrier.

However, unless there is some new radical discovery, you just have to get use to the idea.
There is no other side, your perceived 'other side' is here.
"What you see is what you get".

As for dark matter or energy, probably a legitimate question. But probably should be started in a new thread. Doesn't quite fit into this thread.

Anyone who asks "what is outside of the universe" knows nothing about... the universe. It is an entirely meaningless question. Just like asking "what happened 'before' the universe'". Meaningless garbage. The universe is all there is. No outside of it.

If we are talking about inflationary multiverses, we can define "outside" differently, but that is a different matter.

If you want to believe the universe is expanding, fine, but it's just expanding. Not expanding into something. It's expanding in the sense that things are getting further apart. Period.

Anyone who asks "what is outside of the universe" knows nothing about... the universe.

Are you serious ?

The only people who question, imagine, wonder about 'meaningless garbage' are the ones who understand the universe. People used to think that there was nothing outside our solar sistem, that our solar sistem was all there was. Exactly what you just said, "meaningless garbage" was also told to Galileo and all the other pioneers of astronomy when they started wondering what was outside our planet.

Exactly what you just said, "meaningless garbage" was also told to Galileo and all the other pioneers of astronomy when they started wondering what was outside our planet.

If we assume that the basic things we know about the universe/cosmology/and general relativity are correct (and frankly, we all do), then the comparison there is pretty bad.

If you want to assume that we know absolutely nothing about physics, then sure, let's talk about what's outside the universe and pretend that it's the 1600s.

Unless you are willing to through out general relativity, it is meaningless to talk about what's outside the universe. Throwing out GR is not cool. It was cool for Galleio to through out magic and witchcraft and whatever the hell else they believed then though.

If we assume that the basic things we know about the universe/cosmology/and general relativity are correct (and frankly, we all do), then the comparison there is pretty bad.

If you want to assume that we know absolutely nothing about physics, then sure, let's talk about what's outside the universe and pretend that it's the 1600s.

Unless you are willing to through out general relativity, it is meaningless to talk about what's outside the universe. Throwing out GR is not cool. It was cool for Galleio to through out magic and witchcraft and whatever the hell else they believed then though.

theories change all the time, and to say that anyone who thinks about anything outside the universe does not understand the universe at all is garbage in its own right, because right now not one person understands the universe exactly, this includes you, in 100 years they might have reformulated current cosmology into a model which has things outside of our universe, not saying its probable but dont undermine someones opinion out of ignorance.